Change in serum thyroid-stimulating hormone concentration in response to administration of thyrotropin-releasing hormone to healthy dogs, hypothyroid dogs, and euthyroid dogs with concurrent disease

摘要

Serum thyroxine concentration was measured in 13 healthy dogs, 20 hypothyroid dogs and 18 euthyroid dogs with concurrent disease before and 4 h after administration of 200μg of thyrotropin-releasing hormone (TRH) and serum concentration of thyroid-stimulating hormone (TSH) was measured before and 30 min after TRH administration. Median baseline TSH concentration was 0.25 ng/ml (range, 0.03-0.44 ng/ml) in healthy dogs, 0.93 ng/ml (0.21-3.5 ng/ml) in hypothyroid dogs and 0.21 ng/ml (0.03-0.63 ng/ml)in euthyroid dogs with concurrent diseases. Median percentage change in TSH concentration after TRH administration was 207% (range, 25-2200%) in healthy dogs, 24% (-21-134%) in hypothyroid dogs and 167% (69-1800%) in euthyroid dogs with concurrent diseases. Overall accuracy of using the TRH-induced change in TSH concentration to identify hypothyroid dogs was 90%. It is concluded that percentage change in TSH concentration in response to TRH administration can be used to differentiate euthyroid from hypothyroid dogs, but that the test has little advantage over measurement of baseline TSH and total or free T4 concentration.